Problem: The results of a survey of the 20 families at East Elementary are shown in the graph. During the survey, each family was asked how many children were in their family. How many of the families surveyed had three or more children? [asy] draw((70,0)--(5,0)--(5,55),black+linewidth(1)); draw((0,5)--(70,5),black+linewidth(1)); draw((0,10)--(70,10),black+linewidth(1)); draw((0,15)--(70,15),black+linewidth(1)); draw((0,20)--(70,20),black+linewidth(1)); draw((0,25)--(70,25),black+linewidth(1)); draw((0,30)--(70,30),black+linewidth(1)); draw((0,35)--(70,35),black+linewidth(1)); draw((0,40)--(70,40),black+linewidth(1)); draw((0,45)--(70,45),black+linewidth(1)); draw((0,50)--(70,50),black+linewidth(1)); draw((0,55)--(70,55),black+linewidth(1)); filldraw((10,0)--(10,25)--(20,25)--(20,0)--cycle,gray,black+linewidth(1)); filldraw((25,0)--(25,50)--(35,50)--(35,0)--cycle,gray,black+linewidth(1)); filldraw((40,0)--(40,15)--(50,15)--(50,0)--cycle,gray,black+linewidth(1)); filldraw((55,0)--(55,10)--(65,10)--(65,0)--cycle,gray,black+linewidth(1)); label("5",(0,25),W); label("10",(0,50),W); label("1",(15,0),S); label("2",(30,0),S); label("3",(45,0),S); label("4",(60,0),S); label("Number of Children Per Family",(5,-10)--(70,-10),S); label(rotate(90)*"Number of Families",(-10,0)--(-10,55),W); label("Family Sizes of East Elementary",(0,55)--(70,55),N); [/asy]
Explanation: To determine how many families had three or more children, we need to add the number of families who have $3$ children to the number of families who have $4$ children. We look at the graph and see that there are $3+2=\boxed{5}$ families who have three or more children.